1. Technical Field
The invention concerns a flexible catheter of preferably biocompatible plastic material comprising at least one electrode disposed at the distal end of the catheter for high-frequency therapy of biological tissue.
2. Description of the Background Art
Catheters for high-frequency therapy are basically known. During a high-frequency therapy procedure, the application of a high-frequency ac voltage between two electrodes causes an electric current to be produced in the body tissue between the electrodes, and the result of that electric current is an increase in temperature of the body tissue surrounding the electrodes. With a type of catheter in accordance with this application the electrodes are in electrically conductive relationship with the body tissue after being introduced into a body lumen (for example blood vessel or bile duct) of the patient. The alternating current applied by way of the electrodes is converted into Joulean heat by the ohmic resistance of the body tissue. At temperatures between 50° C. and 100° C., denaturing of the body-specific proteins occurs (coagulation) and as a consequence that involves the area of tissue concerned shrinking or dying off. By virtue of the high current density at the active electrodes the increase in temperature occurs predominantly in the region of those electrodes so that a locally limited thermal use is possible.
U.S. Pat. No. 5,782,760 and WO 2006/017754 A1 disclose catheters for high-frequency therapy of hollow organs.
Catheters for high-frequency therapy of or in hollow organs of the general kind set forth comprise:                a flexible shaft tube of biocompatible plastic material, the internal peripheral surface of which encloses a lumen and the external peripheral surface of which represents the external periphery of the catheter shaft,        a distal shaft portion having at least one electrode for the delivery of high-frequency alternating current to the tissue surrounding the catheter in the treatment situation,        an electric line which is electrically conductingly connected to the electrode and which extends to the proximal end of the catheter, and        a distal end piece fixed to the distal end of the flexible shaft tube.        